I have what is probably a fairly straightforward question for those who know. I've just started playing with some electronics, and I'm a little concerned about frying parts such as transistors and other ICs.
I recall that when attaching things such as LED's to the outputs of ICs, resistors should be used to limit the current passing through the IC. Likewise, current through transistors must be limited.
However, one schematic I've seen attaches a LED directly from the output of a 555 timer to Vcc, and all is well. However, when I, without thinking, hooked up a single transistor and LED (2n3904, with 5V) with no resistors (imagine the basic transistor test circuit but with no resistors), I fried the transistor.
How do you know when a resistor must be used to limit current?
If I were to connect the output of my 555 timer directly to the base of my 3904 transistor and use no resistors anywhere else, will my transistor still fry?
Thanks
I recall that when attaching things such as LED's to the outputs of ICs, resistors should be used to limit the current passing through the IC. Likewise, current through transistors must be limited.
However, one schematic I've seen attaches a LED directly from the output of a 555 timer to Vcc, and all is well. However, when I, without thinking, hooked up a single transistor and LED (2n3904, with 5V) with no resistors (imagine the basic transistor test circuit but with no resistors), I fried the transistor.
How do you know when a resistor must be used to limit current?
If I were to connect the output of my 555 timer directly to the base of my 3904 transistor and use no resistors anywhere else, will my transistor still fry?
Thanks